Long POST times PSU related?

My computer has been taking forever to POST lately. I'm running some tests now on RAM and HDD but what seems to have "fixed" the problem so far is unplugging every USB that I don't need. The POST was taking anywhere from 5-20 minutes to complete and windows told me once to change my visual settings lower due to performance issues. I wasn't doing anything labor intensive, has chrome on with maybe 10 tabs, steam, microsoft words, that's pretty normal.
I'm on a 720w PSU
quad core 9450
6gb ddr2
2 HDDs
HD 6970

It kind of depends. Which 720W PSU do you have exactly? Do you know the make and the model? I'm not recalling any quality-made 720W power supplies at the moment that are 3 years old, but of course that's 3 years ago and I already have like 5 gray hairs!

Well young man (haha), I don't know how this particular PSU rates. I checked two reviews that I found, one at X-bit Labs, and then one at HardOCP (these are links to the Conclusions pages). Both reviews are old, but it sounds like this is/was a good PSU and so this problem might not be related to the PSU.

Although, I don't know for sure and I'd like a 2nd or 3rd opinion from some other PSU enthusiasts on here.

Not at home right now but from memory I think the POST shows the CPU status first, then it checks the memory in the line:
"Memory testing: ####### shared memory" or whatever ###### is the amount of RAM i have I guess.

It gets stuck at "Mem" then after 5-20 minutes the rest of the line filled in and everything is normal. But things probably aren't normal...